This invention relates to a new 2-(1-aryloxy-ethyl)-benzene-1,4-diamine compounds and compositions containing these new compounds as primary intermediates for oxidative coloring of hair fibers.
Coloration of hair is a procedure practiced from antiquity employing a variety of means. In modern times, the method most extensively to color hair is an oxidative dyeing process utilizing one or more oxidative hair coloring agents in combination with one or more oxidizing agents.
Most commonly a peroxy oxidizing agent is used in combination with one or more oxidative hair coloring agents, generally small molecules capable of diffusing into hair and comprising one or more primary intermediates and one or more couplers. In this procedure, a peroxide material, such as hydrogen peroxide, is employed to activate the small molecules of primary intermediates so that they react with couplers to form larger sized compounds in the hair shaft to color the hair in a variety of shades and colors.
A wide variety of primary intermediates and couplers have been employed in such oxidative hair coloring systems and compositions. Among the primary intermediates employed there may be mentioned p-phenylenediamine, p-toluenediamine, p-aminophenol, 4-amino-3-methylphenol, N,N-bis(2-hydroxyethyl)-p-phenylene diamine, 1-(2-hydroxyethyl)-4,5-diaminopyrazole and as couplers there may be mentioned resorcinol, 2-methylresorcinol, 3-aminophenol, 2,4-diaminophenoxyethanol, and 5-amino-2-methylphenol.
There are numerous additional requirements for oxidation dye compounds that are used to dye human hair besides the color or the desired intensity. Thus, the dye compounds must be unobjectionable in regard to toxicological and dermatological properties and must provide the desired hair color with a good light fastness, fastness to a permanent wave treatment, acid fastness and fastness to rubbing. The color of the hair dyed with the dye compounds in each case must be stable for at least 4 to 6 weeks to light, rubbing and chemical agents. Furthermore, an additional requirement is the production of a broad palette of different color shades using different developer and coupler substances. A majority of the desired shades have been produced with dyes based on p-phenylenediamine. However, the use of p-phenylenediamine is being questioned, mainly due to sensitization potential. GB 2,239,265A describes that some individuals are becoming sensitized to p-phenylenediamine and its derivatives. The proposed replacements for p-phenylenediamine have not proved entirely satisfactory. There is therefore a need for new primary intermediate compounds to meet one or more of the desired properties but not possessing the sensitization potential possessed by p-phenylenediamine, that is, which has a weaker sensitization potential than p-phenylenediamine.
It is therefore an object of this invention to provide new primary intermediate compound useful in place of p-phenylenediamine to provide a wide range of different color shades with various combinations of primary intermediates and couplers, but which has a weaker sensitization potential than p-phenylenediamine.
It has been discovered that the new 2-(1-aryloxy-ethyl)-benzene-1,4-diamine compounds are suitable primary intermediates for hair coloring compositions with less sensitization potential than p-phenylenediamine and systems for providing good oxidative coloration of hair and for providing acceptable light fastness, fastness to shampooing, good selectivity, fastness to perspiration and permanent wave treatment, and suitable for providing a wide variety of different color shades with various primary intermediate and coupler compounds.
The invention provides new 2-(1-aryloxy-ethyl)-benzene-1,4-diamine compounds of formula (1): 
wherein R is hydrogen, hydroxy, nitro, amino, halogen, C1 to C5 alkyl or haloalkyl, C1 to C5 alkoxy or cyclic alkoxy, C1 to C5 hydroxyalkyl and C1 to C5 hydroxyalkoxy; Ar is an aromatic group, preferably an aromatic group selected from a furanyl, thienyl, pyridinyl, phenyl, 2,3-dihydro-benzo[1,4]dioxin-5 or-6-yl or benzo[1,3]dioxol-4 or -5-yl group; and y=1 to 3. The halogen may be fluorine, chlorine, bromine or iodine, preferable fluorine or chlorine.
These novel primary intermediates are used to provide coloration to hair in which there is good dye uptake by the hair and provides shades or colors which are stable over a relatively long period of time. The novel primary intermediates provides for dyeing of hair to impart color or shades that possess good wash fastness and do not undergo significant changes on exposure to light, shampooing or perspiration.
Preferred compounds of formula (1) of this invention are those wherein R is hydrogen, amino or C1 to C3 alkyl, and Ar is phenyl, pyridinyl, furanyl, 2- or 3-thienyl, 2,3-dihydro-benzo[1,4]dioxin-5 or -6-yl or benzo[1,3]dioxol-4 or -5-yl.
The new 2-(1-aryloxy-ethyl)benzene-1,4-diamine compounds of formula (1) of this invention can be prepared according to the following reaction sequence, where R1 and R2 are as defined hereinbefore. 
In this synthesis procedure reduction of a compound of formula (2) with a reducing agent such as sodium borohydride (NaBH4) produces a compound of formula (3). Catalytic hydrogenation of the compound of formula (3) provides a compound of formula (4). By tert-butoxycarbonylation of the compound of formula (4) with di-tert-butyl dicarbonate ((Boc)2O) in acetonitrile gives the compound of formula (5). Subjecting the compound of formula (5) to the Mitsunobu reaction with a compound of the formula HOxe2x80x94Arxe2x80x94(R)y in the presence of triphenyl phosphine and diethyl azodicarboxylate or diisopropyl azodicarboxylate produces a compound of formula (6). Treatment of the compound of formula (6) with methanolic HCl results in a compound of formula (1) of this invention.